The system-integrated modular advanced reactor (SMART) new phase (SMART-P) with a rated thermal power of 65.5 MW is currently being developed at the Korea Atomic Energy Research Institute. It is an innovative design to achieve a high degree of safety by adopting inherent safety-improving features and passive safety systems. Realistic and conservative calculations and a parameter study for a steam-line pipe break have been carried out by means of the TASS/SMR code. A set of transients for the whole system of SMART-P is investigated from the point of view of fuel integrity. The results of the analyses show that the most conservative initial conditions are thermal design flow, high system pressure, high coolant temperature, and high core power. It is also assumed that off-site power is unavailable and the steam section pipe guillotine break with the least reactive control rod assembly stuck out in the fully withdrawn position is a limiting case under the most moderator density reactivity condition. The SMART-P safety systems function properly and thus secure the reactor to a safe condition with respect to the safety parameters such as the critical heat flux ratio and the pressure. Natural circulation is well established in the primary and passive residual heat removal systems and is enough to ensure a stable plant shutdown condition after a reactor trips.